1. Technical Field
The following description relates to one or more techniques to avoid unnecessary correction for canceling deviations of image forming positions in an image forming device.
2. Related Art
An image forming device such as a color electrophotographic printer has been known, which includes a plurality of image forming units aligned along a sheet carrying belt such that toner images of respective different colors are sequentially transferred by the image forming units onto a sheet being conveyed on the sheet carrying belt. In such an image forming device, when positional deviations are caused among the respective toner images transferred onto the sheet by the image forming units, a formed image becomes a low-quality one.
In order to secure the quality of the image, a technique referred to as registration for correcting the positional deviations among the toner images transferred onto the sheet has been employed. According to the correction technique, a predetermined pattern is formed on a surface of the sheet carrying belt by each image forming unit, and the positional deviations between different color toner images are determined by detecting the pattern using an optical sensor. Then, based on the positional deviations determined, the image forming position by each image forming unit is corrected.
Meanwhile, in the image forming device, the accuracies of the image forming positions are likely to vary due to operations of opening and closing a cover, and therefore it may lead to the deviations of the image forming positions. For example, Japanese Patent Provisional Publication No. HEI11-95628 discloses an image forming device configured to detect deviations of image forming positions in response to detecting a cover closing operation, determine correction values for canceling the deviations, and perform a printing operation on the basis of the determined correction values in response to a print request.